Fig. 7. Effect of Euro 5 and Euro 4 DEPs, before any after-treatment, on IL-18 production evaluated in Normal Human Bronchial Epithelial (NHBE) cell supernatants.

Cytokine release was analyzed using a commercially available ELISA kit. NHBE cells were stimulated for 24 h with Euro 5 and Euro 4 DEPs, before any after-treatment. After cell exposure to DEPs, supernatants were collected and analyzed. All the supernatants were run in quadruplicate in three different assays (N = 3) and the results are shown as mean ± SD. For 3.3 μg/cm²: P = 0.0089 Euro 5 vs untreated; P = 0.0004 Euro 4 vs untreated; P = 0.0059 Euro 5 vs Euro 4. For 6.6 μg/cm²: P = 0.0018 for Euro 5 vs untreated; P = 0.0016 for Euro 4 vs untreated; P = 0.0002 for Euro 5 vs Euro 4. For a dose-depending comparison: P = 0.0004 Euro 5 3.3 vs 6.6 μg/cm²; P = 0.032 Euro 4 3.3 vs 6.6 μg/cm²